Numerous systems have been devised for the removal of refrigerants from refrigeration systems into storage cylinders or tanks. There has been increasing recognition that to permit the escape of the refrigerant, for example, by bleeding it into the atmosphere may adversely affect the ozone layer and otherwise be environmentally unsafe. A particular problem associated with the efficient removal of refrigerant from larger commercial systems is the ability to maintain as much of the refrigerant as possible in a liquid state for its rapid removal and to liquefy any of the refrigerant in a gaseous state through a compressor and condensor system without exposing the compressor to any of the liquid refrigerant.
U.S. Pat. No. 4,646,527 to Taylor employs discharged gas to heat the incoming refrigerant to boil off the refrigerant and remove the contaminants as opposed to allowing the refrigerant to remain in liquid form or to promote its liquefication prior to removal. U.S. Pat. No. 4,981,020 to Scuderi allows the liquid refrigerant to enter a receiver but there is no heat exchanger in the receiver and no means for pumping the liquid directly into the recovery tank or cylinder and relies instead on pressure differential to remove the refrigerant. Further, the liquid refrigerant is collected in one receiver and bypassed around the compressor section to another receiver then discharged by the discharge pressure of the compressor but does not either pump the liquid refrigerant or chill the refrigerant in the receiver. In U.S. Pat. No. 4,967,570 to Van Steenburgh, Jr., compressor gas is used to vaporize the refrigerant as opposed to keeping it chilled then converts into a liquid but does not use a heat exchanger to keep the incoming gas chilled by means of a separate compressor system. U.S. Pat. No. 4,993,461 to Yamane condenses the vaporized refrigerant but attempts to liquefy it in a recovery tank, and an accumulator is used to assist in reducing the compressor load.
In U.S. Pat. No. 4,809,520 to Manz et al, the heat exchanger is used to vaporize the refrigerant and a liquid pump is used to recycle the refrigerant but not to draw directly out of the system being drained. In U.S. Pat. No. 4,856,289 to Lofland, a pressure regulator is used to vaporize the refrigerant but does not employ a heat exchanger or other cooling medium nor does he employ a liquid pump which permits large amounts of refrigerant to be transferred in short periods of time.
It is therefore desirable to provide for an efficient removal or recovery system for refrigerant from large commercial systems as well as smaller systems which will maintain as much of the refrigerant as possible in liquid form and further will promote liquefication by immediate transfer to a heat exchanger so as to speed the recovery process by removing the liquid and creating a lower temperature source for the gaseous refrigerant. Further it is desirable to employ a heat exchanger utilizing the discharge gas to heat the incoming gas into the compressor so as to prevent liquid from reaching the compressor, an accumulator being used to prevent the liquid refrigerant from entering the compressor; and a crankcase pressure regulator at the inlet to the accumulator reduces the compressor load and enables the compressor to pump all types of refrigerant without damaging the compressor while permitting the gas to become fully liquefied in the condensor.